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copied!<p><strong>Quick Suggestion</strong></p> <p>Read Sequence Diagrams as a two-dimensional flow chart diagram (activity diagram), like a chessboard.</p> <p><strong>Long Boring Extended Answer</strong></p> <p>Imagine a chessboard, where eack square or cell it a place you are moving a figure. The same goes with Sequence Diagrams.</p> <p>In a sequence diagrams there are columns, where there is an instance of a class (actor, table, boundary, any object), and there rows, where operations are performed.</p> <p>Imagine that you have a figure that its doing an operation, at time, like the flowcharts, each time an operation or "message" its performed, the figure moves to the next square or cell or block.</p> <p>Some "cells", of the board, are in the same column (object lifeline).</p> <p>Sometimes, I draw Sequence Diagrams with linelifes with partitions to help me remember that each partition is a cell or a place where an operation it been performed.</p> <pre><code>....................................................... .........+--------------+............+--------------+.. .........| * : FooClass |............| * : BarClass |.. .........+------+-------+............+------+-------+.. ................|...........................|.......... ................|...........................|.......... ............+---+---+...................+---+---+...... .....start..| | |......enter()......| | |...... ..(*)======>| | |==================>| | |---+.. ............| | |...................| | |...|.. ............+---+---+...................+---+---+...|.. ............| | |.......return......| | |...|.. ........+---| | |<------------------| | |<--+.. ........|...| | |...................| | |...... ........|...+---+---+...................+---+---+...... ........|...| | |....PlayChess()....| | |...... ........+-->| | |==================>| | |---+.. ............| | |...................| | |...|.. ............+---+---+...................+---+---+...|.. ............| | |.......return......| | |...|.. ........+---| | |<------------------| | |<--+.. ........|...| | |...................| | |...... ........|...+---+---+...................+---+---+...... ........|...| | |..HaveRootBeer()...| | |...... ........+-->| | |==================>| | |---+.. ............| | |...................| | |...|.. ............+---+---+...................+---+---+...|.. ............| | |......return.......| | |...|.. ........+---| | |<------------------| | |<--+.. ........|...| | |...................| | |...... ........|...+---+---+...................+---+---+...... ........|...| | |...GetSandwich()...| | |...... ........+-->| | |==================>| | |---+.. ............| | |...................| | |...|.. ............#"""+"""#...................+---+---+...|.. ............! | !...GetFriesAlso()..| | |...|.. ............! | !...............+---| | |<--+.. ............! | !...............|...| | |...... ............#"""+"""#...............|...+---+---+...... ............! | !...............|...| | |...... ............! | !...............+-->| | |---+.. ............! | !...................| | |...|.. ............#"""+"""#...................+---+---+...|.. ....finish..| | |...................| | |...|.. ...(O)<-----| | |<------------------| | |<--+.. ............| | |...................| | |...... ............+---+---+...................+---+---+...... ................|...........................|.......... ................|...........................|.......... ................|...........................X.......... ....................................................... </code></pre> <p>The lifelines, indicates that an operation or "message" is performed by an specific object, note, in the example, that some part of lifelines have different characters ("colors") to indicate when an object its idle or busy.</p> <p>Cheers.</p>

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